<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="./jq.js"></script>
  <style>
    #result {
      width: 300px;
      height: 200px;
      border: 1px solid #000;
    }
  </style>
</head>
<body>
  <button id="btn">点击发送请求</button>
  <div id="result"></div> 

  <script>
    const btn  = document.getElementById('btn')
    btn.onclick = function () {

      const xhr = new XMLHttpRequest()

      xhr.open('GET', 'http:127.0.0.1:9000/cors')

      xhr.send()

      xhr.onreadystatechange = function () {
        if(xhr.readyState === 4) {
          if(xhr.status >= 200 && xhr.status<300) {
            console.log(xhr.response)
          }
        }
      }
    }


  </script>
</body>
</html>